I built 18+ client-side dev utilities in Next.js 16 with 0 server latency and no tracking

Like many software engineers, I frequently need quick tools: decoding JWT tokens, formatting messy JSON payloads, beautifying SQL queries, generating UUIDs, or converting cURL commands into clean Python or fetch scripts.

However, almost every online utility has two major flaws:

1. Intrusive Ads & Popups: Slow load times and distracting banners.
2. Security & Privacy Risks: Shady third-party backends logging confidential customer data, API keys, and auth headers.

Why DevToolKit Pro?

I built DevToolKit Pro to solve this completely.

• 100% Client-Side Air-Gapped Execution: Every calculation, conversion, and decoding runs locally in your browser using the native Web Crypto API and WebAssembly. Zero data is ever sent over the network.
• Sub-2ms Telemetry: Zero server roundtrips means instant execution on your CPU.
• 18+ Integrated Tools:
  • JSON Formatter & Minifier
  • JWT Token Decoder (with live expiration check)
  • SQL Beautifier & Keyword Indenter
  • cURL to Fetch / Axios / Python Requests Converter
  • Text & Code Side-by-Side Diff Checker
  • Real-time Regex Tester
  • SHA-256 / MD5 Hash Generator
  • QR Code & UUID v4 Generator
  • Base64 & URL Encoders/Decoders
  • Unix Timestamp & Color Converters

Live Production Demo

Try it free here: https://devtoolkit-pro-seven.vercel.app

The entire project is built with Next.js 16 (Turbopack), React 19, and Tailwind CSS v4.

I'd love to hear your feedback: what developer utilities do you find yourself needing most often in your daily workflow?